FIG. 13 shows a construction of a conventional packet communication network in a mobile communication, and FIG. 14 shows a control sequence diagram employed in this construction.
In FIG. 13, a packet switch 110 includes a signal processor 111. This signal processor 111 is interconnected with an external packet switch (for example, a packet switch in an integrated services digital network ISDN!) . Upon receipt of a packet addressed to one of the mobile terminals within the network, the signal processor 111 transfers the packet to a packet switch 120. This packet switch 120 includes a subscriber information memory 122 in which subscribers information of the individual mobile terminals is stored. The subscriber information includes identification numbers of the individual mobile terminals, service information indicating the contents of services (for example, whether the individual mobile terminals subscribe to the packet service or not) for the individual mobile terminals, location information showing the zones where the individual mobile terminals are currently located.
The signal processor 121 included in the packet switch 120 reads the subscriber information of the mobile terminal 40 as the address of the packet from the subscriber information memory 122 and makes a judgment as to whether or not a service can be offered to the mobile terminal 40, based on the service information stored in the subscriber information memory 122. If the judgment result is affirmative, the signal processor 121 transfers the packet to a packet switch 30 corresponding to the zone shown in the location information. Although FIG. 13 shows only one packet switch 30, actually, a number of similar packet switches are installed and administrate their own zones, respectively.
With the above-mentioned arrangement, however, it was difficult for other communication methods (for example, voice communication method) to commonly use the contents of the subscriber information memory 122 because the subscriber information memory 122 is installed within the packet-specific switch 120. Another problem was that since the packet transferred from the external packet switch must be transferred to the mobile terminal 40 essentially via at least three packet switches, the transmission speed is decreased.